The invention relates to roller skis.
Roller skis are very short skis that have front and rear wheels and are used as training devices for skiers when snow is not available. Typically, the rear wheel includes a clutch that prevents rotation in the reverse direction. In the U.S. and Europe, roller skis are typically used on roads, although in Scandinavia and Central Europe a large number of roller ski tracks have been built in the last few years. Physiological studies have shown that roller skiing is the best non-snow training method for maintaining and improving the cardiovascular and neuromuscular functions required for competitive skiing, particularly cross country racing.
In order to promote duplicating the feel and action of regular skis on snow, rolling resistance of roller skis has been increased by using mechanical friction devices and/or wide, soft rubber tires. Mechanical friction devices wear and require adjustment, in addition to adding weight to the ski, and soft tires tend to wear rapidly, requiring frequent replacement.
A tire member 10 of a wheel of a prior art roller ski is shown in FIG. 1. It includes elastomeric tire 12 (typically having a measured Shore Scale A durometer of 50-58) mounted on hub 14. Bearings are received in outer annuler recesses 16, and an axle would typically pass through the bearings. Some prior art tire assemblies 10 include edge portions 18 having an increased radius of curvature in order to increase the area of contact during edging (when the ski and the user's foot are at an oblique angle with respect to the ground) at the expense of reducing the amount of surface of crown 20 in contact with the ground during normal operation.